This story is all over the net now.
I can see how this works. Modern cars use CAN bus to interconnect the various functional modules, and Chrysler kindly added an in-car entertainment (ICE) box which contains a 3G modem (i.e. it is a computer with internet access). This box probably is, like most consumer IT gear these days, an ARM or 80×86 CPU board running Linux. Then, stupidly, they implemented a network (i.e. bidirectional) bridge between the internet end and the CAN interface…
It also seems that the car is constantly online and reporting its type, GPS position and other stuff to the manufacturer, and this data can be tapped into.
What I don’t get is how you could target a particular person without their co-operation. I am sure they are not issuing SIM cards with fixed IPs (they do exist but are not easy to get) so you would need to trick the driver to e.g. access a website (assuming the car has a web browser) whose server log you can access, and then you have the IP. The car is sure to be behind a NAT router so you have a couple of minutes to establish and maintain two-way comms.
The above also means that if some really bad mistakes were made, one could control an airliner via its satcomms (ACARS, or engine data reporting) connection.
Peter wrote:
one could control an airliner via its satcomms (ACARS, or engine data reporting) connection.
Isn’t that the wet dream of (some of) ATC?
And isn’t that the whole purpose of CPDLC? Ok you might need to press some acknowledge button…
Oh yes it is. I got told off for turning away from the circuit (eg towards the CTR boundary not the runway) 500m too early yesterday departing from Geneva.
My eUp has VW car-net 
I can check “everything” online on my mobile phone, start/stop charging, start the air condition etc, lock doors and it also show where it is parked. In case of a collision, data is sent directly to VW (kind of spooky and cool at the same time), sending position and god knows what else.
I can honk the horn of my i3 from my mobile phone. I gave the car to a friend once and then honked the horn repeatedly. I managed to do it while he was stopped at a red traffic light behind a police car. Now try explaining to the police that it wasn’t him who honked that horn
They’ve disabled the horn-honk feature now (in the UK at least)… You can still flash the lights though!
I bet you can re-enable it with the obligatory bootleg copy of VAG-COM (Ebay) and the ODB2+CAN cable 
I disabled Justine’s DRLs (a VW bodge – full headlamps H24!) in minutes.
There is a limit to how much time the hackers spend working out the confidential bit patterns in the CAN module pages, so there is much more in there which is not yet accessible (unless you want to “play around”).
Peter wrote:
I disabled Justine’s DRLs..
Because driving with full headlamps in daylight is stupid. Volvo made it a trademark many years ago but in the UK it is generally regarded as stupid. DRLs are supposed to be small lights next to the headlamps. Also VW had no legal reason to do this; it was mandatory on cars introduced post-2011 but hers wasn’t.
But via CAN you can also do stuff like disable the non-driver-side door non-opening feature, which some people like and some don’t. And loads of stuff like beeps on the remote unlock…
It isn’t a Volvo trademark – it’s a nordic country trademark (something to do with longer nights at higher latitudes).
